| As an important part of the glulam timber frame structure,the research on the mechanical properties of the beam-column joints has always been concerned.The beam-to-column joints with glued-in rods are considered as a connection form that can effectively improve the stiffness and bearing capacity of the connection parts,but the ductility and energy dissipation capacity of the joints are often reduced due to the influence of the failure mode of post-installed rebars.This thesis aiming at the obvious bond-slip phenomenon between FRP and the wooden base material in the test process of existing FRP-reinforced glulam beam-column with glued-in rods joints,based on the bond-slip and debonding problems of the bond interface,a mechanical performance analysis method of FRP-reinforced beam-column with glued-in rods joints considering bond-slip is proposed.The finite element models of the joints are established by using the cohesive elements which reflects the parameters of the bond-slip constitutive model,combining the skeleton curve and local stress state of the joints by the pseudo-static tests of the reinforced planting bar joints,and the mechanical properties of FRP reinforced joints with and without cohesive elements are further compared to confirm the applicability and rationality of the proposed bond-slip model and analysis method,which provides a reference for the engineering design and theoretical research of modern wood structures.The main research work is summarized as follows :(1)Based on the research and application of bond-slip models of FRP bond-strengthened structures at home and abroad,the characteristics of different acquisition methods of bond-slip model are compared,and the test method suitable for FRP-glulam interface bonding performance is established.The results show that the interface performance of FRP-wood can be studied by single shear test,and the bond-slip curve is obtained by indirect derivation.(2)The single shear test based on different bond lengths was used to analyze the bonding properties of GFRP-glulam and CFRP-glulam interfaces.Based on this,the bond-slip constitutive model suitable for the two FRP materials to strengthen the glulam beam-column joints was established.The results show that the bond length significantly affects the bond capacity between FRP and wood,and the interfacial bonding performance of GFRP-glulam is better than that of CFRP-glulam.The bilinear model can well describe the bond-slip constitutive model of FRP-glulam interface.(3)The finite element model of FRP reinforced glulam beam-column joints considering bond-slip was established.The key parameters of bond-slip model were realized by cohesive elements,and compared with the pseudo-static test results of reinforced joints to verify the validity of the model.The results show that the skeleton curves obtained by the finite element simulation based on the cohesive elements are in good agreement with the skeleton curves obtained by the pseudo-static test of the joints,and the failure modes of the simulation and test specimens are consistent.(4)By comparing the analysis results of the finite element model with cohesive elements and the model without considering bond slip,the influence of bond-slip model on finite element analysis can be explored,which can further verify the accuracy of cohesive zone model.At the same time,based on the models considering bond-slip,the different strengthening effects of GFRP and CFRP are proved.The results show that the error of the finite element analysis results based on the cohesive elements is obviously reduced,and the debonding process of the reinforced joint is effectively reflected.The strengthening effect of GFRP-reinforced beam-column with glued-in rods joints is better than that of CFRP reinforced joints,and the debonding speed is slower in the later stage of loading.The CFRP analysis results without considering the cohesive elements show that the bearing capacity of the CFRP reinforced joints is much higher than the test results,and there is a serious misjudgment.The analysis method based on the cohesive element can avoid this misjudgment. |
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